Low cycle fatigue analyses of open-celled aluminum foam under compression–compression loading using experimental and microstructure finite element analysis

2019 ◽  
Vol 797 ◽  
pp. 231-236 ◽  
Author(s):  
Behrang Hamidi Ghaleh Jigh ◽  
Hossein Hosseini-Toudeshky ◽  
Mohammad Ali Farsi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aluminum Foam ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Compression Loading

A Nonlinear Dynamic Reduced-Order Model for a Large Gas Turbine Outer Casing Low Cycle Fatigue Prediction

2021 ◽  
Author(s):  
Aditya Dubey ◽  
Rishi Relan ◽  
Uwe Lohse ◽  
Jaroslaw Szwedowicz
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Gas Turbine ◽  
Nonlinear Dynamic ◽  
Low Cycle Fatigue ◽  
Reduced Order Model ◽  
Cycle Fatigue ◽  
Order Model ◽  
Element Analysis ◽  
Reduced Order

Abstract The secondary stresses that result from nonlinear and transient thermal gradients during the start-up and shut down of the large gas turbine engines drive low-cycle fatigue at specific locations of the outer casing. Typical service inspection of the outer casing is primarily based on finite element analysis estimates, considering various safety factors. However, as finite element analysis includes the worst possible combination of loading scenarios and operating conditions any engine may encounter in actual operation, this results in a conservative estimation of the service interval. Therefore, a generic preventive maintenance plan for the whole fleet often underutilises the casing capability and added cost. Hence, this paper proposes a data-driven nonlinear dynamic reduced-order model developed using the temperature data from low-cycle fatigue critical casing locations, ramp rates, and the percentage load of operation to predict the stresses. As a result, a reduced-order model can assess the damage for low-cycle fatigue critical locations in real-time using the operational data and propose an appropriate service intervention plan for each casing in a fleet.

Experimental fatigue characterization and elasto-plastic finite element analysis of notched specimens made of direct-quenched ultra-high-strength steel

2016 ◽  
Vol 231 (22) ◽  
pp. 4209-4226 ◽  
Author(s):  
Mohammad Dabiri ◽  
Matti Isakov ◽  
Tuomas Skriko ◽  
Timo Björk
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Strength Steel ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Cyclic Softening ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Notched Specimens ◽  
Ultra High Strength Steel

The low-cycle fatigue behavior of a direct-quenched ultra-high-strength steel was experimentally characterized and numerically modeled. Fatigue and cyclic parameters were obtained by conducting strain-controlled low-cycle fatigue tests on uniform-gage specimens. Surface residual stresses were minimized and axial deflection eliminated by optimization of machining parameters and post-machining electro-polishing. The steel material showed cyclic softening and decrease in yield strength. Cyclic softening, stabilized response, and the cyclic stress–strain curve were numerically simulated using finite element analysis with a model capable of describing nonlinear kinematic-isotropic hardening. The results showed good agreement with experimental values and validated the model’s ability to simulate the softening and cyclic stabilization of the material under investigation. The same numerical method was then used in elasto-plastic stress–strain analysis of notched specimens made of the same material to make fatigue life predictions. Estimated lives were compared with predictions made by analytical approximations such as the linear rule, Neuber’s rule, and the strain energy density method and verified by experimental data. Finite element analysis using stabilized cyclic response yields the most accurate predictions and, thus, provides an effective tool for the fatigue analysis of this material.

Low Cycle Fatigue Tests and Simulations on Steel Elbows

2013 ◽  
Author(s):  
Patricia Pappa ◽  
George E. Varelis ◽  
Spyros A. Karamanos ◽  
Arnold M. Gresnigt
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Local Strain ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Out Of Plane ◽  
Strain Gauge Measurements ◽  
Number Of Cycles

In this paper the low cycle fatigue behaviour of steel elbows under strong cyclic loading conditions (in-plane and out-of-plane) is examined. The investigation is conducted through advanced finite element analysis tools, supported by real-scale test data for in-plane bending. The numerical results are successfully compared with the experimental measurements. In addition, a parametric study is conducted, which is aimed at investigating the effects of the diameter-to-thickness ratio on the low-cycle fatigue of elbows, focusing on the stress and strain variations. Strain gauge measurements are compared with finite element models. Upon calculation of local strain variation at the critical location, the number of cycles to fracture can be estimated.

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